Greenhouse Gas Offsets in a Domestic Cap-and-Trade Program

November 2008

This brief presents the key issues and identifies options for the incorporation of greenhouse gas (GHG) offsets into emerging U.S. climate change policy. A GHG offset represents a reduction, avoidance, destruction, or sequestration of GHG emissions from a source not covered by an emission reduction requirement. The elimination of GHG emissions can be converted into tradeable offset credits, and cap-and-trade programs can be designed to permit firms to use these credits to meet their compliance obligations. A carefully crafted and implemented offset program can significantly reduce cap-and-trade compliance costs by providing lower cost emission reduction options. Yet, while economic modeling has shown that incorporation of offsets into a cap-and-trade program can significantly reduce costs and allowance prices, their inclusion is not without controversy or complication. Some are concerned that offset inclusion will reduce the price signal to the point that the innovation and technological change needed to address the climate problem will be diminished. Others focus on the difficulty associated with substantiating offsets as real emission reductions. Important considerations in designing offset programs include the way in which offsets are defined; the types, location and quantity of offsets allowed; and the methods for assessing and crediting projects. Generally speaking, offset projects come in three distinct types: 1) direct emission reductions, 2) indirect emission reductions, and 3) sequestration. Before a project can create an offset credit, the emission reductions should meet all of the following criteria: they must be real, measurable, additional, permanent, monitored, independently verified, measured from a credible baseline, not represent leakage, and be able to convey as a clear property right. Additionality is perhaps the most important yet complicated issue, as it requires an assessment of what would have happened in the absence of the project. Offset project assessments can be either project specific or standardized. A hybrid assessment approach, which uses some standardization methodologies but allows for a degree of flexibility in assessing projects, may be the most effective. Each of these important factors for creating high quality offsets are discussed in this brief.